In our Australian Patent Application No. AU-A33725/84 we have described a system for the restraint and manipulation of sheep during an automated shearing process. Further research has shown that the apparatus described in this patent application has a number of shortcomings for continued use in an automated shearing environment and it has been concluded that the apparatus could not be readily adapted or modified to meet at least the more important performance features, including:
(i) Independence to sheep size.
(ii) Ease and reliability in loading and unloading sheep.
(iii) Minimum changeover time to unload and reload a sheep.
(iv) Minimum manipulation between productive shearing.
(v) Suitability for access for wool removal.
(vi) Access for shearing free of restraints etc.
(vii) Access for long productive shearing blows.
(viii) Degree of surface conditioning possible.
(ix) Suitability for segregating the belly wool and crutchings.
(x) Wool flow--lack of interference of shorn wool with the shearing task (both severance, sensing and vision).
(xi) Suitability for one piece fleece removal.
(xii) Suitability for in line fleece conveying from the cradle.
(xiii) Simplicity of the cradle.
(xiv) Protection of mechanisms from contaminants.
(xv) Suitability for simultaneous shearing and manipulation.
(xvi) Clarity of exposure for vision sensing.
(xvii) Safety for animal at all times, including ease of emergency release.
While not all of the above features are of significant importance, each of the features require some consideration and any device which meets of the criteria set out above would be regarded as being worthy of further investigation.
Our further research on the apparatus described in the foregoing patent application indicated the following shortcomings:
(i) It does not provide adequate access free from restraint mechanisms to permit productive shearing.
(ii) It requires excessive manipulation without any possibility of concurrent shearing.
(iii) It will be difficult, and possibly unreliable, to automatically load and unload.
(iv) It will take excessive time to load and unload.
(v) It would be impossible to effectively provide for safe and productive human intervention.
(vi) Each unit would likely need its own sheep feed system.
(vii) Wool removal would be most difficult and impossible to execute in one piece.
(viii) The cradle would not be simple or easy to protect from contaminants.
(ix) As noted above it would have a limited sheep size range capability.
(x) The intervention of restraint mechanisms would degrade any vision sensing capabilities desired.
On the basis of the above, it was concluded that further development or modification of the apparatus described in the foregoing patent application was not warranted.
A large number of sheep restraining cradles have been proposed over the years but most of these offer only rudimentary restraint and little or not capacity for manipulation. One recently developed cradle which does offer some advantageous features, particularly ease of loading and unloading, is described in Australian Patent No. 550883. However, this cradle still has several disadvantages, the most notable being the location of the drive mechanism for rotating rollers at each end of the rollers, the positioning of the means for pivoting the cradle assembly, the need for manual intervention in the loading, elevation and unloading of the cradle, and the inability to swivel and tilt the cradle while the animal is at least partly restrained.
In addition to the above, the need to pivot the cradle assembly, while offering a boon to the farmer-shearer by significantly reducing in the effort required in loading and unloading the sheep, complicates the cradle construction and operation and seriously compromises the mechanics of any associated restraining and manipulating devices required for the automated shearing process.
A further problem associated with any attempt to automate the shearing process is involved in the transportation of the sheep from a catching station to the restraining and manipulating means which must form part of any automated shearing system. In order to achieve the full benefits of automation, the sheep must be transported from the catching station to the manipulating and shearing station in a manner which ensures that they remain properly restrained for presentation in a predetermined and reproducible manner. Prior art attempts to automate the shearing process have involved conveyor systems by means of which the sheep are supported by their front or rear legs for presentation to one or more shearing stations. Such an arrangement does not ensure that the sheep are presented to the shearing station in an accurately reproducible manner, and this method of supporting the sheep is also inappropriate for other reasons, including discomfort of the animal.